Method and apparatus for treating liquids



Jan., 7, 1930., .1. R. MCDERMET METHOD AND APPARATUS FOR TREATINGLIQUIDS Filed Sept. 5, 1924 2 Sheets-Sheet l INVENTOR Jan. 7, 1930. J.R. McDERME-r 1,742,999

METHOD AND APPARATUS FOR TREATING LIQUIDS Filed Sept. 5, 1924 2Sheets-Sheet 2A INVEN-roR ',q Ma

7m`mw Patented Jan. 7, 1930 UNITED STATES PATENT OFFICE.

JOHN 1%. MCDERMET, OF J'EANNETTE, PENNSYLVANIA, ASSIGNOB T0 ELLIOTTPANY, F PITTSBURGH, PENNSYLVANIA, A CORPORATION 0F PENNSYLVANIA METHODAND APPARATUS FOR TBEATING LIQUIDE Application led September 5, 1924.Serial No. 738,087.

The present invention relates broadly to the degasiflcation ordeaeration ofliquids, and more particularly to the treatment of feedwater. such for example, as fed to boilers,

5'economizers and the like, for eifecting the removal of air and otherentrained gases therefrom.

It has heretofore been proposed to utilize heaters of the through orthoroughfare l0 type, both in condensing and non-condensing plants. Ithas also been proposed to use heaters of the induction type' in asimilar manner. y, Each of these types of heaters is well knowncommercially and each is recognized as having certain desirablecharacteristics. As disclosed in my copending applications, Serial N o.535,744.- filed February 1l, 1922 and Serial No. 582,151 filed August16, 1922, very advantageous results may be produced by combining the twotypes of heaters in such manner that they both operate on the waterbeing'treated, each heater modifying theaction of the other. -This broadcombination is covered in my applications referred to. d 4

It will be understood that the term thoroughfare heater as used isdefinitiveA of the type of heater, preferably of the open contact type,havin an excess Iof steam supplied thereto over an above that requiredto heat the water, both the heating steam and the excess steam ente inthe heater and the excess then passin ot er connections. Itscharacteristic, t erefore, is that there is a thoroughfare flow of steamthrough the heating chamber and this is the only oonstructionallimitation which the designation of t-he heater carries with it. Theterm induction heater as used herein is deinitive of the type of heaterin which the steam is drawn thereinto by the cooling effect of the waterbeing heated. Preferably, the water in distribute condition is heated bcontact with the steam. Its characteristic, therefore, is an inducedflowwhich is generally proportionate to the work being done, and this'is the only constructional limitation which the designation ordescription carries with it.

For purposes of a clearer understandin of the present invention, it maybe pointe out that the air content dissolved, in water is partly afunction of Water temperature and partly a function of air tension inthe atmosphere in which the water is agitated, as, for example, aheater. The minlmum air ten# sion, and therefore the ideal limit whichcan be secured in a heater of the open contact type in which steam isthe heating medium,

is obviously the ai-r tension of the incoming steam. This is almostinfinitesimal, particularly where the steam has been generated fromdegasified water. Any process of condensation by decreasing thecondensible portion of the heating medium inevitably increases thenoncondensible portion thereof, which is air. f

From the standpoint of air tension, a thoroughfare heater is highlydesirable, as it is able to approach the ideal limit referred to,

provi ded the condensation of steam which occurs therein issubstantially inappreciable. From an economical standpoint, however, aythoroughfare heater is not desirable in vmost lpower plants, becausethe uncondensed steam passing therethrough to other connections isordinarily not recoverable.

An in( uction heater, on the contrary, operates in a different sensefrom a heat balance standpoint in that virtually all the steam coming toit is utilized, neglecting onl the small lamount which passes therefromt rough the vent as a mixture with air. The induction heater, therefore,by condensing substantially all of the condenslble portion ofthe vapor'vmixture coming to it, necessarily increases the proportion of air. Thisis undesirable from the standpoint of deaeration. From the heat transferstandpoint, however, without regard to deaeration the inductionheater ismuch more eficient and to a large extent is4 the only commerciallyutilized heater in power plants.

' I have discovered that it is possible to so combine these two ty "esof heaters that the thoroughfare heater ctions primarily for the purposeof deaeration, and the induction `heater primarily for the purpose ofheating the water before it passes to the thoroughfare heater. While thedivision of work may be varied as desired, it is preferable that thethoroughfare heater be devoted to the duty of deaerating without doingsubstantially any heating, its capacity being based upon the fact thatnone of'its tray surface is devoted to heating. In like manner, theinduction heater should be devoted substantially en-V tirely to heatingduty without any attempt at the process of deaeration therein. Thisdivision of work is desirable for the obvious reason that if the majorpart of the heating medium is condensed in the induction heater and themajor part of the heating is accomplished in this heater, virtually allof the heating medium coming to the thoroughfare heater will ass to theinductionheater. By reason of t is condition, the thoroughfare heaterwill have the advantages of the two fundamentals of high temperaturewith correspondingly low air solubility, and low air Lensionsubstantially equivalent to that of the heating medium.

From practical experience I have found that a combination of heaters ofthe character referred to gives most satisfactory performance andoperates very advantageously at low initial air content. It is to be eX-pected, however, that any air liberated in the thoroughfare heaterultimately arrives in the induction heater, since the two heaters are inseries. Having arrived in the induction heater as one component of amixture, its relative amount is increased due to the condensation in theheating process ofthe other component, which is steam. The airconcentration in the inductionheater limits the temperature of the waterleaving the heater and accordingly the amount of air liberated in' thedeaeration process, to a certain degree, alters the temperaturerelationship between the two heaters and inevitably in a series effect,one heater of which is designed to do no heating, the failure of one ofthe heaters to heat imposes the heating duty on the other.

As the result of the foregoing, with high initial content in the waterto be deaerated, it is impossible by a practical arrangement of sizes toso perfect the combinationy that the ideal upon which the design isbased, namely that the thoroughfare heater do the deaerating and theinduction heater the heating, is possible of attainment. The liberationof air depreciates the performance of the induction heater and when thisperformance is depreciated, the necessary heating capacity to attain thedesired temperature must be assumed by the thoroughfare heater. The trayareas in the thoroughfare heater, however, are proportioned from thestandpoint of deaeration, and any use of them for purely heatingpurposes depreciates the whole unit as a deaerator. p

From a practical standpoint, it is necessary if the unit is to be asuccessful dcaerator, to have the water arrive in the thoroughfareheat-er at substantially the temperature of the steam, since nodeaeration can be accomplished until such a temperature has beenreached. The present invention has primaily for its object the provisionin a combination of heaters of this charatcer, of means to insure thedesired temperature in the water supplied to the thoroughfare heaterwhereby the thoroughfare heater is relieved of the duty of heati-n suchas would be imposed thereon by the ailure of the induction ,heater undernormal conditions of high initial air content.

In the accompanying drawings, I have shown for purposes of illustrationonly, a preferred embodiment of the present inventlon, it beingunderstod that the drawings do not define the limits of myy invention,as changes in the cons-truction and operation disclosed therein may bemade without departing'from the spirit of the invention or scope of mybroader claims.

In the drawings:

Figure l is a 'diagramatic side elevation, partly broken away, of oneform of apparatus for carrying out the present invent-ion;

Figure 2 is a vertical transverse sectional Vview through the apparatusillustrated in Figure 1, certain of theparts being shown in elevation;and

Figure 3 is a detail view, illustrating a slightly modified embodimentlof the invention.

In carrying out the present invention, there may be provided aninduction heater 2 having a manifold 3 for suplying the water to betreated, the outletsy from the manifold preferably discharging above aplurality of spray pans or other agitating means 5 over f.

which the water is adapted to flow in' cascade. The induction heater ispreferably in superimposed relationship to a thoroughfare heater 6 havinone or more vapor connections 6a extending upwardly therefrom and intothe induction heater. Liquid from the induction heater is adapted toflow into the thoroughfare heater through one or more connections 7,each communicating at one end with the bottom of the induction heaterand at the other end discharging into the upper portion of thethoroughfare heater. The thoroughfare heater is also preferably providedwith agitating means 8 herein illustrated as comprising a series of pansarranged .to cause the entering liquid to flow through vthe vapor spaceof thel thoroughfare heater other tube pass 14 to the connection 15leading to the manifold 3. Within the connection 15 is arranged a valve16 adapted to be automatically operated in accordance with the liquidlevel in the thoroughfare heater by means of a float 17 operativelyconnected thereto. The vapor space of the induction heater has anoperative connection 18 Iwith the vapor space of the condenser 9.

Arranged within each of the water connections 7, preferably adjacent theend thereof, communicating Wlth the induction heater 2 is a steaminjector 19 which may comprise a plurality of tubes communicating' witha header 20 having a steam inlet 21. Preferably these tubes extend intothe connections 7 in such manner as to discharge steam in the directionof the flow of water therethrough. lt is well recognized that anyattempt to 1nject steam below the surface of a body of water meets aresistance equal to the hydrostatic head of the submerged orificethrough which the steam is to be discharged. lf, however, the steam isdischarged into a pipe line in which the direction of the steam dischare and the direction of the water flow are t e "-same,the two factorswill be mutually acceleradvantage that it is readily accessible and canbe repaired without the necessity of going into the interior of eitherof the heaters. During the operation of the apparatus there will usuallybe a solidbody of water within the connections 7, thereby insuringeiiicient heat interchange by this steam injection. lt furthermore makesit unnecessary to utilize any of the capacity of the induction heaterfor the concentrating of a solid body of water and insures a lessexpensive initial cost for the reason that the induction heater may bedesigned solely from the standpoint of heating surface.

In practice, the steam for operating the injector nozzles approximatesabout l2 inches of mercury and may be derived from a separate source ofsteam supplyjor by a reducing back ressure valve incorporated in thesteam supp y line, this valve being of a pressure loaded type so as toimpose sucient pressure on the line to create the. temperaturediderential of approximately 12 inches of mercury to operate the jet andpermit any surplus of steam amounting in practice to approximately 98percent to pass onward and enter the thoroughfare heater and fulfill itsnormal function.

In the accompanying drawings I have illustrated the latter method ofsteam supply comprising a main inlet 22 leading directly to thethoroughfare heater 6 and having therein a diderentially unbalancedvalve 23 which may be loaded in any desired manner, as by a spring 24.Steam may be supplied to the valve 23 through a connection 25 having abypass cooperating with the connection 21 for supplying the steam to theauxiliary heating means within the connections 7.

ln some cases it may be desirable to operate the apparatus at atemperature corresponding to a pressure which is below atmosphericpressure. ln such cases the ondenser 9 will tend to withdraw thereleased vapors and gases from the apparatus and thereby maintain thedesired thermal conditions therein. lt will be understood that for thispurpose the particular design of the condenser may be changed inaccordance with the conditions under which it is desired to operate theapparatus. By utilizing such a condenser, not only are the'desirablethermal conditions maintained within the heater, but the sensible heatof the released vapors andgases is conserved and imparted to theincomingwater for preheating the same. l

When operating under subatmos heric conditions as just described, itwill obvious that there may exist within the steam supply connection 25a steam pressure which is also subatmospheric. As the present state ofthe art dictates the advisability of maintaining steam supply linesunder a pressure which is at least atmospheric, it is undesirable tohave the pressure conditions within the connection 25 transmitted to thesteam supply line 26.

lf such conditions were maintained in the steam supply line, there wouldbe a correspending tendency toward air infiltration which would not onlycontaminate the Water but would impair the eiiiciency of the apparatus.ln order to prevent such an lindesirable condition, there may beprovided within the line 26 a balanced valve structure 27 having apiston or diaphragm 28 subjected on one side to atmospheric pressurethrough a port 29 and on the other side to pressure within theconnection 25 through a passage 30. The pressure within the connection25 may be adjustably augmented by a loading spring 31 whereby thedesired operating conditions of the valve will be insured. ln thismanner either atmospheric orsubatmospheric conditions may be maintainedin the supply line 26, irrespective of the conditions existing withinthe apparatus or the connection 25.

`With contemplated developments in the art,

4the use of a balanced valve in the steam supply line may be renderedunnecessary as the supply of steam at subatmospheric pressures may bemade possible. lt will be understood tot i l out.

therefore that while such a valve, or some equivalent means, is bothnecessary and de-` sirable in certain installations, the .operation ofthe present apparatus is not. necessarily dependent thereon in certaincases.

If desired, I may substitute for the balanced valve' a thermostaticvalve operated in accordance with the temperature within the inductionheater, as disclosed in my copending'application Serial No. 582,151,hereinbefore referred to. Such a modification is illustrated in Figure3. In this figure there is illustrated a valvel 32 having a controllingelement 33 within the induction heater, preferably adjacent the bottomthereof, so as to be within the comparatively small body of liquidmaintained therein by reason of the location of the inlets to theconnections 7. In this manner the admission of steam to the thoroughfareheater is regulated in propor-v tion as the admission of water to theinduction heater varies the temperature therein. In accordance with thepresent state of the art, it is customary vto withdraw the exhauststeam, which is almost universally employed as heating steam for boilerfeed water, from the auxiliaries which produce it at substantiallyatmospheric pressure. It may -be desirable, however, as before referredto, to effect deaeration at temperatures below atmospheric, for examplebetween 140 and 212c F. If atmospheric steam in excess is admitted tothe thoroughfare heater, it will obviously be impossible to maintain thede` sired low pressure temperature therein while, on the other hand, ifa deficiency only of steam is available, the pressures would drop belowatmospheric and a vacuum would be produced on the valve 32. Without thevalve this pressure would be transmitted t0 the supply line with theobjections before pointed This makes it only necessary to protect theapparatus per se against air infiltration. The thermostatic valve, whereemployed, further constitutes an automatic means for prevent-ing unduecondensation of steam within the thoroughfare heater, such as wouldimpair its operating efficiency.

If it were possible in commercial practice to obtain steam for heatinpurposes entirely free of dissolved gases, ie operation 0f an apparatusof this character would be greatly simplified. As this is not possible,however, the provision of the vents orconnections 18 for the inductionheater for the purpose of removing non-condensible gases therefrom isnecessary. It is impossible in condensation work to secure an entirelysteam-free vent mixture and these vents therefore conduct a mixture ofsteam and air. vSince the induction heater is of necessityAa/goodheating means but an imperfect condensing means, this vent may at timescarry away a very considerable portion of steam which without thecondenser 9A would represent a loss. The

Vejector 11 cooperating with the condenser by its aspirating actioninduces a steam How into the thoroughfare heater, through such heaterand then into the induction heater, the

condensible portion being condensed within the condenser and the heatthereby recovered.

It is desirable that the heat exchange means comprisingv the inductionheater, the thoroughfare heater and thepcondenser shall all operateunder a vacuum corresponding very closely lto atmospheric pressure,minus the vapor tension of the water in the induction heater. Thecondenser is therefore further desirable, as it obviates the necessityof providing an ejector having an air ejecting ca-` pacity large enoughfor aspirating a large quantity of steam from the induction heater.

The condenser by its action secures economy in ejection capacity. Ifther condenser was of suiicient capacity to'accomplish its duty4automatically, there wouldbe a rush of steam through the thoroughfareheater into the induction heater and thence into the condenser. Bymaking the condenser of proper size,

there is provided an automatic regulation inthat if its heating duty isexceeded,'the ejectionI capacity of the ejector will be automaticallydiminished by reason of the overload of steam received thereby. It willbe apparent that the value ejection capacity as used herein its rated intermsof air or non-condensiblegas removal Where a reduction 1n ejectioncapacity, as referred to, will automatically lower the vacuum andincrease the absolute pressure in the induction heater. As the pressurein this heater rises, the temerature will also tend to rise, therebytending to limit the further admission of steam to the thoroughfareheater either through the balanced pressure valve or the thermostaticvalve.

During the operation of the apparatus, cold water enters the condenserand recovers the heat from the vented mixture and then c passes lnto theinduction `heater flowing therethrough in broken up condition and then ypartial air tension ywithin the thoroughfare eater, it is to be expectedthat under certain conditions the air concentration in the inductionheater may `reach such a point as to interfere with the desiredtemperature con-V ditions therein. In such cases the admission of steamthrough the auxiliary heating means 19 enables the desired temperatureconditions to be maintained and the water supplied to the thoroughfareheater without throwing any additional load onto the thoroughfare heatersuch as would impair its eiiiciency from a deaerating standpoint. Inactual practice an amount of steam will be supplied to the auxiliarylheating means suflicient to at least raise the temperature of the waterpassing through the connections 7 by an amount equal to the depressionin the induction heater by reason of-increased air concentrationtherein.

In order to provide a continuous record of temperature, and to providefor accurate regulation of'temperature, there may be provided anindicating or recording thermometer connected -to both the induction and4thoroughfare heaters.

The accompanying drawingsmay be considered as largely diagrammatic forthe purpose of illustrating the invention. For the sake of a clearunderstanding, I have illustrated the heaters as comprising separatechambers. It will be obvious, however, that the same operation andresults would te obtained by providing a common enclosing shell with athoroughfare tray section or compartment and an induction tray sectionor compartment. In such a` construction the entering water would iirstpreferably pass, as illustrated, through the vent condenser asthecooling medium for the vented vapors which lleave the inductioncompartment or heatingsectionof the deaerating apparatus; this waterwould be distributed by the tray section in the induction compartment.The entering steam would pass horizontally through the lower for airseparating tray compartment. In passing through this compartment, thesteam sweepsthe air with it and then rises vertically through the portor ports provided, to the heating or induction compartment. The water inv turn Hows through the connections provided into the lower ordeaerating compartment, whereby a counter dow of air and water isobtained.

The advantages of the present invention ffision in an apparatus of. thischaracter of ,means permitting operation at any desired temperatureconditions without dan er of air infiltration into the steam supply ineand without the possibility of steam Waste from. theapparatus.

said heater, means controlling the lsteam supi ply to said heaterthrough said inlet to prevent increase in air tension therein, heatingmeans inducing a steam 'low through the heater `and supplying heatedwater to lsaid connection, and means in said connection for supplyingadditional heat to the water therein. l

' 3. In a feed water treating apparatus, a thoroughfare heater, aninduction heater for delivering heated water thereto, a vapor connectionbetweenl said heaters, a water connection between said heaters, andmeans for injecting steam into the water passing from the inductionheater to the thoroughfare heater through said water connection.

4. In an apparatus for heating and deaerating water, a plurality ofheating means in series, a pipe connection for passing heated liquidfrom one of said heaters to the next heater of said series, and means insaid pipe connection for further heating the water fio-wingtherethrough.

5. An apparatus for deaerating liquids, comprisin two separate sets ofliquid agitating and liquid passes in" series, means for supplying steamto the systems in series with the steam supply initially to the systemlast receiving liquid, and heating means intermediate the systems forcompensating for temperature depression in the first system.

6. An apparatus for deaerating liquids, comprising two liquid agitating.and distributing systems over which the liquid passes in series, meansfor supplying steam to the systems in 4series with the steam supplylinitially to the system last receiving liquid, and heating meansintermediatethe systems for injecting steam into the liquid in the d1-rection of its flow.

mediate the systems for inpctlilnglstean into t e iqui conthe liquidpassing throug nection to maintain a constant temperature of liquid tothe last system irrespective of initial air content of the liquid,

'stributiiig trays over which the y 8. Apparatus for deaerating liquids,comprising a lower tray section, an upper tray section, connections forfeeding liquid into the uppertray section and thence to the lowertraysection, connections for supplying` steam to the lower tray sectionand thence to the upper traysection, and means intermediate the trasections forvarying the temperature of the i u id during its passagefrom one section to t e other. i

9. Apparatus for deaerating liquids, comprising a lower tray section, anupper tray section, connections for feeding liquid into the upper traysection and thence to the lower tray section, connections for supplyingsteam to the lower tray section and thenceto the upper tray section, and'means intermediate the tra sections for injecting steam into the liquidcaving the'uppcrtraysection..

y10. Apparatus for deaerating liquids, com,- prising a lower traysection, an upper tray section, connections for feeding liquid into theupper tray section and thence to the lower tray section, connections forsupplying steam to the lower tray section and thence to the upper traysection, and supplemental heatin means intermediate the tray sections.

11. eaerating apparatus, comprising an induction section, a thoroughfaresection, means for producing a liquid flow through said sections in onedirection and a steam flow through said sections in a counterdirection,Y

and means for injecting steam into the liquid in the ldirection ofliquid flow'duringits passage from one section to theother.

12. Deaerating apparatus,`compris1ng an induction section, a`thoroughfare section, means for producing a liquid flow through saidsections in one direction and a steam flow through said sections in acounter direction,

supplemental Yheating means for the liquid flowing from one sectiontothe other, and liq- Huid distributing means in each of said sections.p I A 13. Deaerating apparatus, comprising an Y induction section, athorou hfare section means l.for producing a liqui ow through saidsections-in one direction and a steam flow through said sections in acounter direction. means for injecting steam into the liquid during itspassage from'one section to the other, and liquid distributing means ineach of said sections. Y 4

14. Decorating apparatus, comprising an induction section, athoroughfare section,

means 'for producing a liquid flow through said'sections in onedirection and a steam flow' v through said sections in a counterdirection means for injecting steam into the` liquil in the direction ofhquid flow during its passage from one section to the other, and liquiddistrbutin means in each of said sections. 15. In a eed water heating sstem, lan induction heater, a thoroughfare eater, a wa ter connectionbetween said heaters constituty ertothe other.

ing a water concentrating space for the inheater, and means deliveringheating steam to the water in said connection.

17. In a feed water heating system, an induction heater, a thoroughfareheater, a water connection between said heaters constituting a waterconcentrating space for the induction heater, means for supplying steaminitially to the thoroughfare heater, means for supplying waterinitially to the induction heater, andv means for injecting heatingsteam intov the water in the direction of itsv flow.

18. In the method of treating li: uid, the steps consisting in heating aliqui by the condensation of a heating medium, passing the heatedliquidl intothe'vapor s ace 0f a second heater, heating the liquid uringits passage to the secondheater before it reaches said vapor space to anamount required to compensate for caused by air concentration during thefirst heating, and controlling the supply of liquid in accordance withdemands for treated liquid. j y A 19. In the method of treatingliquid,.'the

steps consisting in'heating a liquid, passing sage to the second heater4under such conditions that the velocity action df the steamand water ismutually agcelerating l 20. In the method of treating liquid, the

steps consisting in heating a liquid in a heater by vthe condensation ofa heating medium, v

temperature ldepression liopassing the heated liquid to a second heater,

further heating the liquid therein by the condensation of a heatingmedium, and compensating for the decreased heating eiciencyconcentration therein, by` injecting a heating 'medium intothe liquid inthe direction of its travel during its passage from one heat- 21. In themethod oftreating liquid, the

i steps consisting in heating a liquidA by the condensation of a heatingmedium, passing the heated liquid to a second heater, and;

i heating Vthe liquid during its passagejto and: VYbefore it enters thesecond heater to an" 'lac-1:'y

amountrequired to compensate for of the first heater caused,l byincreased air directly thereto.

ature depression caused by air concentration during the first heating.

22. Inthe method of treating liquid, the steps consisting in supplyingthe same to a heater and heating the same therein by an induccdflovv ofheating medium substantially proportional to the Work being done,passing the heated liquid to a second heater, passing the heating mediumfor the first heater through the second heater. maintaining a relativelylow air tension in the second heater by the first heater, and heatingthe liquid during its passage to and before it enters the second heaterto an amount required to compensate for temperature depression in thefirst heater'caused by increased air concentration therein.

23. In the method of treating liquid, the

ste s consisting in supplying the same to an in uction heater, heatingthe same therein, passing the heated liquid to a thoroughfare heaterthrough a de ned liquid flow path, passing the heating medium', from thethorou hfare heater to the induction heater throug a separate definedfiovv path and maintaining a relatively loW air tension 1n thethoroughfare heater by the induction heater, and heating the liquid insaid defined liquid flow path during the flow of the liquid from theinduction heater to the thoroughfare heater. v,

24; Apparatus for deaerating liquids, comprising a plurality of'heatingmeans in series, a pipe connection for passing heated liquid from-'oneof said heaters to the next heater of said series, and heating means insaid pipe connection for further heating the water flowingAtherethrough, said heating means Vhaving a 25. Apparatus for deaeratingliquids, comprising a plurality of heating means in series, a connectionfor passinghheated yliquid from one of said heaters to t c next heaterof vsaid series, and heating means in said connection for furtherheatingA the water flowing 26. Deaerating apparatus,

therethrough, said heatin means having a steam connection leadingirectly thereto for 4 discharging the steam into said liquid in thedirection of liquid flow through-said connection.

comprising separate heatin chambers, water connections for said carnbers, steam connections for said chambers independent of the waterconnections, and means for increasin the temperatureof the Water flowingthrong one of said water connections'.

27. Deaerating apparatus, comprising an induction heater having aplurality of trays therein, a thorou hfare heater having a plurality oftrays t erein, a water connection -from the induction heater to thevthoroughfare heater, a vvapor connection from the thoroughfare heaterto the Ainduction heater,

,steam connection leading and means for increasing the temperature ofthe Water passing through said water connection.

28. Deaerating apparatus, comprising an induction heater having aplurality of trays s therein, a thoroughfare heater having a pluralityof trays therein, a Water connection from the induction heater to thethoroughfare heater,.a vapor connection from the thoroughfare heater tothe induction heater, and means for increasing the temperature of theWater passing through said Water connection, said means comprisingasteam nozzle structure dischargin into the Water in the direction ofWater ow through said connection.

29. Deaerating apparatus, comprising a heating chamber having Vaplurality of trays therein, a second heater having a plurality' of traystherein, means for delivering water to said trays, means for heating thewater in its passage over said trays, a water concentrating spaceintermediate said trays for Water heated in the first heater, and meansfor further heating water in said space during its passa e to the secondheater.

30. n the method of deaerating, the steps comprising subjecting thewater to contact with steam in a plurality of stages and supplyingheating steam intermediate certain of said stages to heat the water andto increase its velocity.

31. Deaerating apparatus, comprising a thoroughfare heater, an inductionheater,

said thoroughfare heater havin a vapor space and a liquid s ace, meansor supplying steam to both o said heaters, means for passing the liquidfrom sald mduction heater to the vapor space of the thoroughfare heater,and means for heating the liquid durprior to entryinto -heater into theinduction heater, and suppl .ing additional heatto the liquid intermeiate 'the' induction heater and the thoroughfare heater.

InI testimonywhereof I have hereunto set m hand.

y JOHN R. MODERMET.

eater, continuously passing-'s'ubstan-y y

